Flexible knee braces are used by athletes and other persons engaged in vigorous physical activity to protect the knee from injury and to avoid exacerbation of existing injury. The knee is one of the most heavily used joints of the body, as it is used in any activity that involves walking or running. The knee is also a common subject of injury, due to the relatively high levels of stress it must bear. During normal ambulation, in occupations involving physical labor, and especially during strenuous sports, the knee can undergo abnormal motions as a result of quick changes in direction, fatigue, uneven surfaces, or impacts. These abnormal motions can cause sprains or more serious injuries, including dislocation, stretching, or tearing of the tissues that make up the knee.
Several different types of abnormal motion can cause injury to the knee. First, hyperextension of the knee joint can occur, wherein the knee flexes in its normal front to back fashion but beyond its normal range of motion. A second type of abnormal motion is axial rotation, wherein the lower leg is twisted rotationally relative to the thigh about the knee joint. A third type of abnormal motion is lateral flexure of the lower leg relative to the thigh, wherein the knee joint flexes from side to side instead of the normal front to back motion. In addition, abnormal motion of the patella (kneecap) can result in injuries such as chondromalacia patella, which is a softening or degeneration of the undersurface of the patella, and dislocation of the patella, also known as subluxation of the patella.
Devices to protect the knee against abnormal motions have been used for many years, in a variety of specific embodiments which vary in their abilities to protect against the different types of abnormal motions. Besides protecting the knee against abnormal motions, the devices sometimes provide additional benefits such as insulating the knee to keep it warm, protecting the knee against impact, or compressing the knee to reduce discomfort. However, the protections afforded by these devices against abnormal motion are often accompanied by a reduction in range or ease of normal motion. These devices can also have other undesirable aspects such as added weight on the leg, potential for self-injury or injury to others caused by rigid components, difficulty of application and removal, cost, appearance, and irritation or chafing of the skin.
For these reasons, there has long been motivation to find an improved knee brace which can protect the knee from abnormal motions without affecting the range or ease of normal motion, while avoiding the undesirable aspects of prior art devices.